This study aims to determine the increase in students' mastery of concepts in Newton's Force and Law material by applying the Discovery Learning model to 10 th grade students of Public Vocational School 1 Bireuen. The research used was quasi-experimental research with Pretest-Posttest Group Design. Data was collected in 10 th grade TKRO (Automotive Light Vehicle Engineering) as an experimental class with 38 students and 10 th grade TBSM (Motorcycle Business Engineering) as a control class with 38 students. Data obtained from the results of this study using SPSS for Windows Version 18. Based on the results of data analysis to see the results of mastery of students' concepts obtained an average value of 85.16 and the control class average value of 79.95. Data obtained from the test results are used to test the research hypothesis using the Independent Sample T-test and N-Gain test. From the results of the analysis obtained from the results of the Independent Sample T-test results of the initial and final test values obtained t coun t> t table is 3.901> 1.992 with sig (2-tailed) of 0.00 lower than 0.05. The N-Gain value in the experimental class was 42.24%. Whereas the control class was 38.96%. The results of the analysis of student responses using the Discovery Learning model obtained the percentage of strongly disagreeing at 8.2%, disagreeing at 12.3%, agreeing at 48.1%, and strongly agreeing at 31.2%. Based on the results of the study it can be concluded that with the Discovery Learning model the mastery of students' concept mastery especially on Newton's Force and Law material is more improved than using conventional …